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MSL - Astronomical Observations, Phobos/Deimos, planetary/celestial observations and more
Phil Stooke
post Aug 3 2013, 03:40 PM
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Here's a comparison - the map image is from here:

http://www.solarviews.com/cap/mars/phobos6.htm

(the image which Tayfun projected onto the shape model originated from USGS as the caption says, but it is the one which I had previously reprojected into modern coordinates. The USGS version was based on an experimental shape model and was badly distorted. I reprojected it cell by cell to fit Damon Simonelli's shape model from Cornell)

Attached Image


Hall crater is visible at the bottom. Kepler Dorsum runs horizontally just above it.

Phil


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Zelenyikot
post Aug 3 2013, 03:48 PM
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I used Celestia and made these images.
Attached thumbnail(s)
Attached Image
 


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iMPREPREX
post Aug 3 2013, 03:51 PM
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That's an incredible eye you have, Phil. Thank you and sorry. smile.gif To the untrained eye though, you have to agree that it could be mistaken for the Stickney.


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Zelenyikot
post Aug 3 2013, 03:57 PM
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QUOTE (iMPREPREX @ Aug 3 2013, 04:51 PM) *
To the untrained eye though, you have to agree that it could be mistaken for the Stickney.

Any big crater on the Phobos is Stickney laugh.gif


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elakdawalla
post Aug 3 2013, 04:16 PM
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Remember that Phobos is synchronously rotating, just like our moon, and Stickey faces more-or-less forward along the orbit, so it's always going to be closer to the limb than to the center of the disk.

A corollary to that is that any spacecraft that either sits on the surface or is in a low, circular mapping orbit (MGS, ODY, MRO) will always only see the Mars-facing hemisphere of Phobos. Only Mars Express and earlier spacecraft have seen other sides.


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ugordan
post Aug 3 2013, 05:08 PM
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There's also what appears to be faint "mars-shine" illuminating Phobos if you play with image brightness:

Attached Image


Do we expect the original raw data to be overexposed, because the thumbnails kind of give the impression that the images are well-exposed?

EDIT: Ahh, I see now. That one full-res image corresponds to an overexposed thumbnail as well. Other shots should look pretty spectacular, then.


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mcaplinger
post Aug 3 2013, 05:17 PM
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QUOTE (ugordan @ Aug 3 2013, 10:08 AM) *
Do we expect the original raw data to be overexposed, because the thumbnails kind of give the impression that the images are well-exposed?

The full-res image you're looking at is from sequence 1424 and the better-exposed thumbnails from sequence 1423, which presumably have different exposure times.


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wildespace
post Aug 5 2013, 09:05 AM
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Zelenyikot's images of Phobos gave me an idea to overlay colour information from the Mastcam image onto the detailed Celestia image:
Attached Image


For aesthtetic purpose, if anything, but I do hope to hear whether the Mastcam really picked those colours, or whether they're just an artifact.


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Phil Stooke
post Aug 5 2013, 11:49 AM
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I'm sorry to say they are artifacts. There are very subtle colour variations on Phobos but not like those.

Phil



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Phil Stooke
post Aug 6 2013, 01:44 PM
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This is a super-resolution composite of five frames from the Phobos-Deimos sequence on sol 351. Four images (in two pairs) of Deimos appear as smudges on each side - one of them shows the position of the dark limb of Phobos. The 'super-resolution' process (combining multiple views, enlarged and sharpened) is mostly just reducing the JPG artifacts here. Now Stickney can be seen at left, where it was overexposed before.

Phil

Attached Image

PS - I don't show it here, but if you increase the saturation in the RGB image you see some color variation - this is real color variation on Phobos, blue around Stickney, red over the northern limb. I say 'real color variation' - not 'true color'!


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fredk
post Aug 6 2013, 01:52 PM
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Nice!

And a quick animation of the frames so far:
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ugordan
post Aug 6 2013, 04:10 PM
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A few frames registered on Deimos and a few frames registered on Phobos stacked and merged. Magnified 2x, sharpened and white-balanced.

Attached Image


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atomoid
post Aug 6 2013, 09:21 PM
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QUOTE (fredk @ Aug 6 2013, 05:52 AM) *
..And a quick animation of the frames so far...

very nice indeed, this actually poses an interesting puzzle. So this is perhaps looking at the eastern horizon before solrise with Phobos soon to set. And it looks like Deimos is going retrograde against the background of stars and that must be due to a parallax effect of the MSL observation point sweeping underneath and overtaking Deimos' actual slower motion in the same direction as Phobos..?

hoping for a m100 transit if the cam can take it, hopefully in the right place to get one as good as the old Oppy one. Colors come out in the HiRise pics..
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jmknapp
post Aug 7 2013, 12:10 AM
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The moons are so tiny, I've wondered if they'd be much to look at "in person," but based on these images it looks to be a very striking sight.

BTW, the NY Times tracking map now pretty much matches the official.


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mcaplinger
post Aug 7 2013, 12:46 AM
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QUOTE (atomoid @ Aug 6 2013, 02:21 PM) *
very nice indeed, this actually poses an interesting puzzle....
hoping for a m100 transit if the cam can take it...

Deimos moves E-W and Phobos moves W-E because of the rotation of Mars, so I'm not sure what your retrograde reference is to.

If you didn't like the grazing observations last year, there are more chances coming up later in the month. http://meetingorganizer.copernicus.org/EPS...PSC2012-326.pdf


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